Health PowerhouseFruits by definition, avocados provide more than 20 key nutrients, including B vitamins, vitamin E, and brain-boosting choline. They also contain copper and zinc and antioxidant pigments that fight inflammation. All this nutritional might does come at a cost: One avocado packs about 230 calories and 21 grams of monounsaturated fats.

Heart ProtectorSome runners avoid avocados because of the fat content, but according to several studies, the fruit helps lower levels of artery-clogging LDL ("bad" cholesterol) and increase levels of HDL ("good" cholesterol). The monounsaturated fats, vitamin E, and polyphenols all seem to work together to boost heart health.

Waist TrimmerResearchers have found that those who routinely eat avocados have a smaller waist size and lower body mass index than abstainers. Avocado eaters also have a lower risk for metabolic syndrome, characterized by high cholesterol, high blood pressure, and high levels of circulating fats—all of which increase the risk of heart disease.

Inflammation FighterEating avocado with a fatty meal may protect blood vessels from inflammatory damage and constriction. A recent study showed that eating a fatty burger topped with half an avocado lessened markers of inflammation and blood vessel constriction compared with eating a burger without it. Researchers theorize that the phenolic compounds in avocado (similar to those in red wine) provide the protection.

Nutrient BoosterMany polyphenols and all carotenes are fat-soluble—meaning they need to be paired with a bit of fat to be absorbed. Studies show that adding avocado to salad, spreading it on whole-grain bread, and using guacamole as a dip help with the absorption of beneficial compounds in these phytonutrient-rich foods.